Reciprocating carriage drawing machine

ABSTRACT

Reciprocating carriage drawing machine includes first guideways extending in a given drawing direction, a drawing carriage reciprocably mounted in the guideways, revolving cam means operatively connected to the drawing carriage for reciprocating the same along the first guideways, an intermediate carriage interposed between the drawing carriage and the cam means for lengthening the stroke of the drawing carriage, the intermediate carriage being also operatively connected to the cam means and being similarly reciprocable thereby in second guideways in the given drawing direction, and step-up transmission means for increasing the length of stroke of the drawing carriage comprising at least one axle carried by the intermediate carriage and extending substantially perpendicularly to the given drawing direction, a pinion loosely mounted on the axle and being in meshing engagement at one side thereof with a stationary rack and on the other side thereof with a rack slidable in third guideways paralled to the drawing direction, the slidable rack being coupled to the drawing carriage.

United States Patent Greven [451 Sept. 26, 1972 RECEPROCATING CARRIAGE [73] Assignee: Schumag Schumacher Metallwerke Gesellschaft mit beschrankter Haftung, Aachen, Germany 22 Filed: July 15, 1970 [21] Appl. No.: 55,092

[30] Foreign Application Priority Data July 16, 1969 Germany ..P 19 36 139.8

[52] US. Cl ..72/287 [51] lint. C1 ..B2lc 1/28 [58] Field of Search ..72/287, 290, 426; 214/1 BB, 2l4/1.1, 1.7

[56] References Cited UNITED STATES PATENTS 2,781,136 2/1957 Sehn et a1. ..214/1 BB 2,910,321 10/1959 Sehn et al. ..214/1 BB 2,943,750 7/1960 Sehn et a1. ..72/426 1,298,999 4/1919 Moltrum ..72/290 2,367,793 1/1942 Mcllvried et al. ..72/290 FOREIGN PATENTS OR APPLICATIONS 456,226 4/1949 Canada ..72/426 Primary Examiner-Charles W. Lanham Assistant Examiner-Michael .1. Keenan AttorneyCurt M. Avery, Arthur E. Wilfond, Herbert L. Lerner and Daniel .1. Tick [57] ABSTRACT Reciprocating carriage drawing machine includes first guideways extending in a given drawing direction, a drawing carriage reciprocably mounted in the guideways, revolving cam means operatively connected to the drawing carriage for reciprocating the same along the first guideways, an intermediate carriage interposed between the drawing carriage and the cam means for lengthening the stroke of the drawing carriage, the intermediate carriage being also operatively connected to the cam means and being similarly reciprocable thereby in second guideways in the given drawing direction, and step-up transmission means for increasing the length of stroke of the drawing carriage comprising at least one axle carried by the intermediate carriage and extending substantially perpendicularly to the given drawing direction, a pinion loosely mounted on the axle and being in meshing engagement at one side thereof with a stationary rack and on the other side thereof with a rack slidable in third guideways paralled to the drawing direction, the slidable rack being coupled to the drawing carriage.

10 Claims, 8 Drawing Figures RECIPROCATING CARRIAGE DRAWKNG MACHINE The invention relates to a reciprocating carriage drawing machine comprising at least one drawing carriage which is reciprocable by a revolving cam in ways in the machine frame parallel to the direction of drawmg.

Among conventional reciprocating carriage drawing machines one in which two draw. carriages and two cams so cooperate that the stock can be continuously drawn straight through the machine is now widely used. This known type of drawing machine is suitable for drawing bar and tube stock even when a very high quality product is required. The stock is drawn in a straight line with a simultaneous reduction in cross section, and at the same time it is straightened. It can be continuously drawn in straight sections, and lengths o the desired size can be cut off.

One objection to these known reciprocating carriage drawing machines is that drawing speeds exceeding about 50 meters/minute are not feasible, more particularly for the following reasons. Each revolution of the mainshaft and each consequent revolution of the cams generates a complete reciprocation of the two drawing carriages. Based on practicable numerical values each drawing carriage may draw the stocka distance of say 450 mm in each reciprocation sothat the stock will be drawn a total distance of 900 mm through the machine in the course of each revolution of the mainshaft. For achieving a drawing speed of 60 meters/minute, the mainshaft in the assumed conditions would have to revolve at a speed of 66% r.p.m.

If this speed were to be raised, the times available for acceleration, deceleration and speed equality of the drawing carriages would become very short and functional imprecision would necessarily be the result. For instance, the transfer of the stock form one carriage to the other might cease to be effected within the very shorttime of speed equality of the two carriages. This would result in a jerky action, possibly with short periods of standstill in the passage of the stock through the machine. Furthermore, between the instant of triggering the closing of the gripping jaws on the carriages and the actual closing of the jaws there is usually a fixed and constant time interval that is inherent in the design of the machine and that may become very noticeable at very high speeds. Practical tests have shown that an increase in the speed of the mainshaft beyond the abovementioned limiting speed causes the resultant irregularities in the drawing action adversely to affect the quality of the product.

Furthermore, an increase in the length of the stroke generated by the cams fails to lead to the desired improvement. Although the paths available for acceleration, deceleration and speed equality of the carriages would be lengthened and the last above-mentioned difficulties would be overcome, any increase in the stroke without a simultaneous increase in the diameter of the cam would involve so considerable an increase in the angular pitch of the cam that no useful construction for dealing with the consequent thrusts would be feasible. On the other hand,- if the original angle of pitch were to be retained then the stroke could be increased only at the expense of a simultaneous enlargement of the diameter of the cam. This would mean a bulkier machine frame, a corresponding increase in the cost of the machine and more floor space for its erection. Also the larger size of the machine would be an inconvenience in operation. Finally, the curved surfaces of cams of major diameter cannot be produced on standard copy milling machines the production of the cams for conventional drawing machines already necessitates full use being made of the available capacity of standard copy milling machines. In other words, special, larger copy milling machines would be needed and this would have very adverse effects upon the coast of production. For large diameter stock a drawing speed of about 60 meters/minute is generally high enough. However, for smaller diameter stock, for instance for the production of copper pipes and for drawing solid bar stock having diameters between 2 and 15 mm, the economy of the machine would be greatly improved if drawing speeds could be increased. The smaller diameter stock also requires lower pulling forces, and the power requirements would in principle still be within admissible limits if the drawing speeds were increased.

Chain and rope type drawing benches operating at speeds exceeding 60 meters per minute are well known in the art. However, these benches are unsuitable for the continuous drawing of stock. The finished lengths of the drawn stock are not arbitrarily selectable since they depend upon the size of the bench.

Higher drawing speeds and a continuous process of drawing can be achieved by using conventional drum or sheave type drawing machines. However the final product obtainable on such machines is in the form of coils or rings. Straight tubes or rods can be obtained only by carrying out a supplementary straightening process. The cross sections that are obtained also tend to deviate from the circular, and to become oval. Furthermore, the internal stresses in the material may vary. Experience has shown that the necessarily following straightening operation particularly in the case of copper tubes, for example, on roller-straightening machines, for instance also usually creates considerable difficulties.

lt is the object of the present invention so to contrive a reciprocating carriage type drawing machine of the first hereinabove specified kind in which at least one drawing carriage is reciprocable by a revolving cam in ways in the machine frame parallel to the direction of drawing, that without any change in the usual speed of the mainshaft, or the usual diameter of the cam, or the usual pitch of the cam, a drawing speed higher than heretofore obtainable can be achieved without adversely affecting the functional cooperation between the parts of the machine and the drawn stock.

With the foregoing and other objects in view, 1 provide reciprocating carriage drawing machine comprising first guideways extending in a given drawing direction, a drawing carriage reciprocably mounted in the first guideways, revolving cam means operatively connected to the drawing carriage for reciprocating the same along the first guideways, an intermediate carriage interposed between the drawing carriage and the cam means for lengthening the stroke of the drawing carriage, the intermediate carriage being also operatively connected to the cam means and being similarly reciprocable thereby in second guideways in the given drawing direction, and step-up transmission means for increasing the length of stroke of the drawing carriage comprising at least one axle carried by the intermediate carriage and extending substantially perpendicularly to the given drawing direction, a pinion loosely mounted on the axle and being in meshing engagement at one side thereof with a stationary rack and on the other side thereof with a rack slidable in third guideways parallel to the drawing direction, the slidable rack being coupled to the drawing carriage.

The provision of the intermediate carriage makes it unnecessary to modify the design of the conventional cam member for the purposes of the invention. The cam may be of the same diameter, its length may be the same and its pitch and speed may be as before. Consequently the intermediate carriage which is reciprocated by the cam moves in principle in exactly the same way and at the same speeds as the drawing carriage in the prior art reciprocating carriage machine. Assuming the above mentioned speed of revolution of the mainshaft of 66%r.p.m. the intermediate carriage will reciprocate at a speed cor responding to a drawing speed of about 60 meters per minute. The axle which is mounted in the intermediate carriage crosswise of its direction of reciprocation, and which carries a loose pinion, participates in these reciprocations one side of the loose pinion rolls on the rack that is affixed to the frame. Consequently the other side of the pinion travels at twice the speed of the intermediate carriage, and thus also covers twice the distance. These movements of the pinion are transmitted to the rack that is slidable in the intermediate carriage in the direction of drawing. Owing to the oneway coupling of the drawing carriage to the sliding rack the drawing carriage also moves twice as far as the intermediate carriage. The times required for the drawing carriage to cover a given distance are equal to the times required for the intermediate carriage to travel half this distance. Therefore, assuming that the speeds of the intermediate carriage correspond to a drawing speed of about 60 meters per minute, the drawing carriage in the proposed arrangement will move at a drawing speed of 120 meters/minute. ln a conventional reciprocating carriage drawing machine comprising two drawing carriages and two cams and equipped according to the invention with two intermediate carriages, the cyclic operations and the available path lengths for deceleration, acceleration and speed equality between the carriages for performing these operations can provide a machine that performs just as reliably at a drawing speed of 120 meters/minute as a machine lacking intermediate carriages and operating at a drawing speed of only 60 meters/minute.

If in the proposed machine the torque of the mainshaft remains the same as before the drawing pull of the machine at a drawing speed of 120 meters/minute will be roughly only half that developed by the prior art machine at a speed of 60 meter/minute. However, this imposes no limitations upon the applicability of the proposed drawing machine since, as already previously explained, the higher drawing speeds are more specifically wanted for drawing stock of relatively smaller diameters, between say 2 and mm, that is to say when the pulling power need not be so high.

The higher expenditure in structural means in the proposed reciprocating carriage drawing machine, due

to the provision of an intermediate carriage, is relatively low. More particularly it is lower than the additional expenditure in means involved in taking alternative steps, such as an increase in the dimensions of the cam unit and a consequent in the overall size of the machine frame.

Unlike conventional chain and rope type drawing benches or drum and sheave type drawing machines the proposed reciprocating carriage machine shares the advantage of the prior art reciprocating carriage machine of permitting the stock to be drawn continuously in a straight line with the highest possible precision.

In a useful further development of the proposed reciprocating carriage drawing machine a fixed rack may be provided on each side of the machine frame and two pinions which are mounted side by side in the intermediate carriage and of which one meshes with one of the two fixed racks and the second with the other of the fixed racks, may both mesh with a sliding rack which is located between the two pinions and which has rack teeth on each side for this purpose.

This form of construction has the advantage that owing to the symmetry of its design forces are generated only in drawing direction and that no lateral or tilting forces arise which could adversely affect and cause wear in the ways. Moreover, each of the pinions and of the two fixed racks need transmit only one half of the total force. This also applies to each set of teeth on the centrally disposed two-sided sliding rack.

In a desirable embodiment of the proposed drawing machine the sliding rack is guided in ways in the intermediate carriage.

This is a feature that avoids structurally more ambitious arrangements of providing ways in the machine frame. Moreover, the provision of ways in the intermediate carriage is better for relatively adjusting the pitch circles of the pinion or pinions and the pitch line of the rack with satisfactory precision and with the aid of simple structural means. In a preferred embodiment of this feature the ways for the sliding rack are integrally formed in a structural element in the intermediate carriage that also contains the pinion axles.

According to another feature of the proposed drawing machine the one-way coupling between the sliding rack and the drawing carriage couples only in the pulling direction.

This feature avoids static over-determination that might lead to jamming or wedging.

However, a particularly desirable feature of the proposed drawing machine comprises ways disposed in tiers for the drawing carriage and the intermediate carriage.

This arrangement avoids the necessity of extending the length of the machine beyond the length of the stroke of the drawing carriage. Overall the machine may thus be of relatively compact design, since the drawing carriage and the intermediate carriage can reciprocate at different level the one above the other.

Yet another feature of the proposed drawing machine comprises the provision of pinions in the form of double pinions having different numbers of teeth on two pitch circles, of which one meshes with the fixed rack and the other with the sliding rack.

This form of pinion enables drawing speeds to be generated that are not double those but less than double those attainable in the described type of prior art drawing machines. For instance, the increase in drawing speed may be only one and a half times the speed of the conventional machine. This lower increase in drawing speed may be better when the stock has a diameter somewhat exceeding say mm, so that, on the one hand, it is desirable to have a drawing speed exceeding 60 meters/minute, whereas, on the other hand, the necessary pulling force would not be available if the step-up ratio were as high as 2 1.

Naturally this feature of providing double pinions in the proposed drawing machine may also be used to increase the stroke length of the sliding rack by more than 2 1. in such a case it may be advisable for the fixed racks to project inwardly sufficiently far from the frame to provide clearance for the accommodation of the larger diameter pitch circle of the double pinions in the machine frame.

Furthermore a desirable arrangement in the proposed drawing machine comprises dividing the pinions and/or the racks in their median center planes and providing means for relatively shifting and locking the teeth of the two halves for the purpose of taking up backlash due to wear of the tooth flanks.

As already described, the cam flights in the propose reciprocating carriage drawing machine may be of the same form of construction as in the corresponding prior art reciprocating carriage drawing machines. However, primarily in view of the much higher speeds attained by the drawing carriages during their reciprocation, it must be borne in mind that particularly high inertial moments are generated at the points of motion reversal. Let a conventional reciprocating carriage drawing machine be considered in which the cam has the form of a cylinder cam on a shaft (mainshaft) extending parallel to the direction of drawing, and in which the cam flight comprises screw or helical portions. In this prior art drawing machine the cam flight projects from the cylinder and has two flanks. One of the following rollers rides on each of these flanks and in the conventional drawing machine the two follower rollers are mounted in the drawing carriage. One of the rollers transmits the working force for the actual draw.

The axle of this roller is fixed in the drawing carriage. The other roller serves for transmitting the force during the return stroke and ensures that both rollers remain continuously in firm contact with the flanks of the cam flight. The axle of this roller is fixed in the drawing carriage. The other roller serves for transmitting the force during the return stroke and ensures that both rollers remain continuously in firm contact with the flanks of the cam flight. The axle of this other roller is resiliently mounted inthe drawing carriage in the conventional prior art arrangement. Since the forces during the return stroke are much smaller than those required for the drawing stroke it is possible without difficulty to ensure that both rollers continuously maintain contact with both sides of the cam. Moreover, in the conventional drawing machine the center distance between the two rollers remains more or less constant during the passage of the cam flight between them. In the conventional drawing machine this is achieved by making the portion of the cam flight generating the return motion which is more steeply pitched in order to accelerate the return, somewhat thinner than other portions. In the prior art drawing machine, in order to maintain a constant center distance between the rollers, the cam flight is widest at the reversal points, slightly thinner along that part which generates the drawing stroke, in accordance with the pitch of this part, and thinnest along the part that generates the carriage return.

In principle the above described design of cam may be adopted unchanged for use in the proposed drawing machine, excepting that the cam in the proposed machine will then cooperate with the intermediate carriage instead of with the drawing carriage. The intermediate carriage in the proposed drawing machine will in such a case preferably be provided with the same kind of follower rollers as above described for cooperation with the flanks of the cam flights. In other words, the roller for transmitting the drawing stroke will be mounted in fixed bearings and that for generating the return motion for keeping the two rollers in contact will be mounted in resiliently yielding bearings.

It has already been mentioned that in the proposed drawing machine, particularly owing to the higher speed attained by the drawing carriage during reciprocation, the inertial forces at the point of motion reversal are higher than in the prior art drawing machine. This may lead to the resilience of the yielding roller not being sufficient to ensure the maintenance of contact between the rollers and the flanks of the cam at the points of motion reversal. A general increase in the biasing spring force at points where higher contact pressure is not needed would merely increase were of the cam flight, particularly in the region which generates the drawing stroke, and which must be specially accurate and precise.

For increasing the biasing spring pressure merely at the points where the cam generates the motion reversal the present invention proposes to widen the cam flight at the reversal points on that side which faces away form the thrust transmitting roller.

This widening of the cam flight slightly increases the center distance between the return roller and the drawing roller at the points of motion reversal and-the stacks of springs which provide the resilient bearing support of the return rollers are thus additionally compressed, their consequent higher thrust then enabling them to maintain contact of the drawing and return rollers with the flanks of the cam even at the points of motion reversal. Elsewhere along the length of the cam flight the contact maintaining thrust will then again be less and equal to that generated in the conventional prior art machine. The widening of the cam flight on the side remote from the drawing roller has the effect that only the return rollers are displaced from their normal path, whereas the drawing rollers continue to ride on the original design path for generating the required reciprocatory carriage motion, despite the widening of the flight.

Moreover, it is preferred in the proposed drawing machine that the one-way coupling between the drawing carriage and the sliding rack should be at the trailing end of the rack when viewed in drawing direction.

The purpose of this is to subject the sliding rack to tension during its working stroke. It can then be of thinner cross section than would be the case if the rack were subjected to compression and to the attendant buckling loads. Since the forces transmitted during return are very much lower the buckling loads during return do not call for a larger cross section.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in reciprocation carriage drawing machine, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of a specific embodiment when read in connection with the accompanying drawing, in which:

FIG. I is a cross sectional view of the machine frame of my invention showing the drawing and intermediate carriages.

FIG. 2 is a plan view of the intermediate carriage, part of the fixed racks secured to the machine frame, and the sliding rack of the invention.

FIG. 3 is a fragmentary longitudinal section, on a smaller scale, of an intermediate carriage, part of the cam, the drawing and return rollers cooperating with the cam, the sliding rack and the one-way coupling between the sliding rack and the drawing carriage constructed according to the invention,

FIG. 4 is a schematic side elevational view, on a still smaller scale, of the drawing machine according to the invention, for continuous drawing, showing two cam members, two intermediate carriages and two drawing carriages.

FIG. 5 is a fragmentary cross sectional view on a scale larger than that of FIGS. 1 and 2, showing a double pinion with different diameter pitch circles bearing different numbers of teeth of provide a transmission ratio in the direction of lengthening the stroke of the sliding rack beyond a ration of 2 l, and also showing the projecting disposition of a fixed rack.

FIGS. 6a and 6b are sectional views at an even larger scale of a divided pinion and adjusting means for relatively adjusting the gear teeth of the two halves for the purpose of taking up backlash due to wear.

FIG. L7 is a view form above, to a scale intermediate that of FIGS. 3 and 4, of a developed part of a cam flight on a cam member in which the cam flight in widened on the side remote from the drawing follower roller in the region of motion reversal of the intermediate carriage.

Referring now to the drawings, there is shown a reciprocating carriage drawing machine according to the invention which for continuously drawing a stock, and as shown in FIG. 4, includes two drawing carriages it), it), two intermediate carriages 4, d and two cylinder cams I, ll The cam flights on these cam cylinders cooperate with follower rollers 2, 3, and 2', 3, and 2', 3 which are mounted in the drawing carriages. The cylinder cams I, i are jointly driven by a mainshaft 114. FIG. 4 also shows the sliding racks 7, '7' and their coupling connections with the drawings carriages Ml, it) by coupling members 9, 9'.

Other important details are shown in FIGS. 1 to 3. FIG. 1 shows the drawing carriage 10 mounted in ways 12 and the intermediate carriage 4 sliding in ways 11. Both pairs of ways are fixed in he machine frame 13. Likewise fixed in the machine frame 13 are stationary racks 8. FIG. 1 also shows a roller 2 which cooperates with one flank of the cam flight on the cam cylinder 1. Axle pins 76 mounted in the intermediate carriage carry pinions 5 which are loose on these axles. The pinions mesh, on the one hand, with the stationary racks 8 and, on the other hand, with a movable rack 7 which is slidably mounted in ways in the intermediate carriage 4. When the intermediate carriage 4 moves, the pinions 5 roll on the stationary racks 8 and propel the movable sliding rack 7 a distance equal to twice the stroke of the intermediate carriage; cf. FIG. 2.

With reference to FIG. 3 it will be understood in detail how the cylinder cam l cooperates with the rollers 2 and 3 of the intermediate carriage 4. During each complete revolution of the cylinder cam l the intermediate carriage 4 performs a complete reciprocation of prescribed stroke, and the sliding rack 7 performs a similar reciprocation of twice the length of the stroke of the intermediate carriage. The coupling member 9 transmits this double length stroke to the drawing carriage 19, but the coupling connection is maintained only in drawing direction.

The provision of an axle pin 6 on each side of the intermediate carriage permits very considerable forces to be transmitted even by simple structural means. The individual path lengths associated on the cam flight with acceleration, deceleration, speed equality, draw and return, are magnified to twice their lengths by the nature of the transmission to the drawing carriage of the proposed machine, without the necessity of providing a cam designed to generate a longer stroke. If in the above described example the total length of the draw during one revolution of the mainshaft in a conventional machine is assumed to be 900 mm, then the proposed drawing machine will provide a corresponding draw of 1,800 mm. Consequently the drawing portion of the proposed drawing machine must be longer than in the corresponding conventional machine. In width theproposed machine may be the same as the conventional machine. The proposed machine does not therefore require any change in the manner in which it is operated. It is also an advantage that the cams which cam in practice are proven thrust generating means can in principle be retained. The operating frequency in the course of each cycle is the same in the proposed machine as in the corresponding conventional machine. The transfer of the stock from one carriage to the other in the proposed machine proceeds within a path length of speed equality that is twice that available in the conventional machine. Consequently the proposed machine functionally ensures that the stock will be continuously drawn without jerks and irregularities.

The doubled length of the drawing stroke of both drawing carriages in the proposed drawing machine also has other advantages, namely in the context of the gripping of the stock by the jaws on the drawing carriages. The pointed beak of the stock is gripped between the jaws of the first drawing carriage and pulled forward through the dieplate by the length of the stroke of the drawing carriage. During the second draw the entire length of the jaws of the first drawing carriage will already grip the surface of the stock, whereas in a corresponding conventional machine of the previously prescribed kind this will not be the case and the full length of the jaws will not yet come into contact with the drawn surface of the stock. This is a particularly useful feature when drawing a tube stock. When the proposed drawing machine is used for drawing a tube stock the process of drawing-in is substantially improved by the doubling of the length of the drawing stroke.

In the embodiment illustrated in FIG. axle pins 19 are provided in the intermediate carriage l8, and double pinions l7 and 17" are loosely mounted on these pins. A rack 16 is affixed to project from the machine frame 15. The pinion l7 meshes with this fixed rack 16, whereas the pinion 17" meshes with a rack 7 that is slidably mounted. in this embodiment the length of the stroke of the rack 7 may be more than twice the length of the stroke of the intermediate carriage 18 by an amount equal to twice the ratio of the number of gear teeth of the tow two pinions l7 and 17". It will be understood that the projection of the rack 16 from the side of the framing provides the necessary clearance for the larger diameter pinion 17" to be accommodated in the machine frame 15.

For the following explanations reference will be made to FIGS. 6a and 6b. In order to ensure that the drawing carriages move smoothly, particularly through their reversal points, the teeth of the pinions must mesh with the racks with as little backlash as possible. For this purpose means must be provided to compensate wear on the tooth flanks. This can be done by a divided form of construction of the pinions and by relatively adjusting or resetting the teeth 20 and 21 of the two halves. The tooth width must be so designed that the teeth 20 and 21 on each half can transmit the full load. For the purpose of relatively shifting and locking the tooth flanks of the teeth 20 and 21 two holes 23 are located on a pitch circle 25 in the upper half of the pinion, whereas the lower half of the pinion is provided with two coneddepressions 22' that are off-center in opposite directions with respect to the holes in the upper half of the pinion. With the aid of grub screws 24 having a coned point the teeth 20 and 21 can thus be relatively moved. The upper and bottom half of the pinion are then clamped firmly together by screws 24 engaging tapped holes 26. The clearance between tooth flanks is not adjusted until the pitch circle of the pinion and the pitch line of the rack are tangent. For this purpose the axis of the pinion is eccentrically mounted. The pinions are first adjusted with reference to the sliding rack 7 in the middle. When this has been done the outer racks 8 are adjusted in the machine frame with reference to the adjusted position of the pinion.

The following explanations make reference to H6. 7 of the drawings. Owing to the inertial forces the roller 2 may lift off the tracks 29, 30 at the points of pitch reversal of the cam flight l. The center distance between the rollers 2 and 3 should normally remain constant. In order to ensure that this also applies at the reversal points the stack of springs 28 at these points would have to provide several times the biasing thrust needed elsewhere. Since increased biasing thrust of the spring stack 28 along the forward nand return paths 29 and 30 is unnecessary and may even be undesirable, the spring stack 28 in a machine according to the invention is given the usual bias and the necessary increase in thrust at the reversal points 27 is obtained by increasing the center distance between the two rollers 2 and 3 at these points, and by thereby increasing the compression of the stacks of springs 28. This step ensures that the rollers 2 and 3 sill maintain contact with the cam. The shape of the cam 29, 30 must, of course, not be changed because this determines the character of carriage reciprocation. Consequently the cam flight must be thickened on that side 31 of the flight which faces away from the rollers 2 which take the load at reversal.

I claim:

- 1. Reciprocating carriage drawing machine comprising first guideways extending ,in a given drawing direction, a drawing carriage reciprocably mounted in said first guideways, revolving cam means operatively connected to said drawing carriage for reciprocating the same along said first guideways, an intermediate carriage interposed between said drawing carriage and said cam means for lengthening the stroke of said drawing carriage, said intermediate carriage being also operatively connected to said cam means and being similarly reciprocable thereby in second guideways in said given drawing direction, and step-up transmission means for increasing the length of stroke of said drawing carriage comprising at least one axle carried by said intermediate carriage and extending substantially perpendicularly to said given drawing direction, a machine frame, two stationary racks mounted on opposite sides of said machine, frame, said transmission means comprising two pinion means mounted side-by-side on said intermediate carriage, said two pinion means being in respective meshing engagement at one side thereof with said stationary racks and on the other side thereof with a rack slideable in third guideways parallel to said drawing direction, said slideable rack being disposed between said two pinion means and carrying rack teeth on each side thereof respectively meshing with said two pinion means.

2. Reciprocating carriage drawing machine comprising first guideways extending in a given drawing direction, a drawing carriage reciprocatingly mounted in said-first guideways, revolving cam means operatively connected to said drawing carriage for reciprocating the same along said first guideways, an intermediate carriage interposed between said drawing carriage and said cam means for lengthening the stroke of said drawing carriage, said intermediate carriage being also operatively connected to said cam means and being similarly reciprocable thereby in second guideways in said given drawing direction, and step-up transmission means for increasing the length of stroke of said drawing carriage comprising at least one axle carried by said intermediate carriage and extending substantially perpendicularly to said given drawing direction, pinion means loosely mounted on said axle and being in meshing engagement at one side thereof with a stationary rack and on the other side thereof with a rack slidable in third guideways parallel to said drawing direction, said slidable rack being coupled to said drawing carriage by a one-way coupling effective only in said given drawing direction.

3. Reciprocating carriage drawing machine compris- -ing first guideways extending in a given drawing direction, a drawing carriage reciprocably mounted in said first guideways, revolving cam means operatively connected to said drawing carriage for reciprocating the same along said first guideways, an intermediate carriage interposed between said drawing carriage and said cam means for lengthening the stroke of said drawing carriage, said intermediate carriage being also operatively connected to said cam means and being similarly reciprocable thereby in second guideways in said given drawing direction, and step-up transmission means for increasing the length of stroke of said drawing carriage comprising at least on axle carried by said intermediate carriage and extending substantially perpendicularly to said given drawing direction, pinion means loosely mounted on said axle and being in meshing engagement at one side thereof with a stationary rack and on the other side thereof with a rack slidable in third guideways parallel to said drawing direction, said slidable rack being coupled to said drawing carriage, said third guideways being mounted on said intermediate carriage and said first and second guideways for said drawing and said intermediate carriages respectively, are mounted in rails located above one another.

4. Reciprocating carriage drawing machine comprising first guideways extending in a given drawing direction, a drawing carriage reciprocably mounted in said first guideways, revolving cam means operatively connected to said drawing carriage for reciprocating the same along said first guideways, an intermediate carriage interposed between said drawing carriage and said cam means for lengthening the stroke of said drawing carriage, said intermediate carriage being also operatively connected to said cam means and being similarly reciprocable thereby in second guideways in said given drawing direction, and step-up transmission means for increasing the length of stroke of said drawing carriage comprising at least one axle carried by said intermediate carriage and extending substantially perpendicularly to said given drawing direction, pinion means loosely mounted on said axle and being in meshing engagement at one side thereof with a stationary rack and on the other side thereof with a rack slidable in third guideways parallel to said drawing direction, said slidable rack being coupled to said drawing carriage, said pinion means being in the form of a double pinion, the pinions of said pinion means having different numbers of teeth, one of the pinions of said pinion means being in meshing engagement with said stationary rack and the other of the pinion of said pinion means being in meshing engagement with said slideable rack.

5. Machine according to claim 1 wherein each of said pinion means is in the form of a double pinion, the two pinions as each of said pinion means having different numbers of teeth, one of the two pinions of each of said pinion means being in meshing engagement with said stationary rack, and the other of the two pinions of each of said pinion means being in meshing engagement with said slidable rack.

6. Machine according to claim 5 wherein said double pinions have a transmission ratio lengthening the stroke of said drawing carriage beyond a ration of 2 1, said stationary racks extending inwardly for a distance affording space within said machine frame for accommodating the larger of the two pinions of each of said pinion means.

7. Reciprocating carriage drawing machine comprising first guideways extending in a given drawing direction, a drawing carriage reciprocably mounted in said first guideways, revolving cam means operatively connected to said drawing carriage for reciprocating the same along said first guideways, an intermediate carriage interposed between said drawing carriage and said cam means for lengthening the stroke of said drawing carriage, said intermediate carriage being also operatively connected to said cam means and being similarly reciprocable thereby in second guideways in said given drawing direction, and step-up transmission means for increasing the length of stroke of said draw- I ing carriage comprising at least one axle carried by said intermediate carriage and extending substantially perpendicularly to said given drawing direction, pinion means loosely mounted on said axle and being in meshing engagement at one side thereof with a stationary rack and on the other side thereof with a rack slidable in third guideways parallel to said drawing direction, said slidable rack being coupled to said drawing car riage, said pinion means being formed of two parts meeting in a median center plane thereof, and means for relatively adjusting and locking the teeth of both said parts thereof for equalizing wear of the flanks of the teeth.

8. Reciprocating carriage drawing machine comprising first guideways extending in a given drawing direction, a drawing carriage reciprocably mounted in said first guideways, revolving cam means operatively connected to said drawing carriage for reciprocating the same along said first guideways, an intermediate carriage interposed between said drawing carriage and said cam means for lenghtening the stroke of said drawing carriage, said intermediate carriage being also operatively connected to said cam means and being similarly reciprocable thereby in second guideways in said given drawing direction, and step-up transmission means for-increasing the length of stroke of said drawing carriage comprising at least one axle carried by said intermediate carriage and extending substantially perpendicularly to said given drawing direction, pinion means loosely mounted on said axle and being in meshing engagement at one side thereof with a stationary rack and on the other side thereof with a rack slidable in third guideways parallel to said drawing direction, said slidable rack being coupled to said drawing carriage, said racks being formed of two parts respectively, meeting in a median center plane thereof, and means for relatively adjusting and locking the teeth of both said parts thereof for equalizing wear of the flanks of the teeth of said racks.

9. Reciprocating carriage drawing machine comprising first guideways extending in a given drawing direction, a drawing carriage reciprocably mounted in said first guideways, revolving cam means operatively connected to said drawing carriage for reciprocating the same along said first guideways, an intermediate carriage interposed between said drawing carriage and said cam means for lengthening the stroke of said drawing carriage, said intermediate carriage being also operatively connected to said cam means and being riage, said intermediate carriage having load-bearing rollers engageable with one side of a flight formed on said rotary cam, said flight being widened on a side thereof facing away from said load-bearing rollers in a region of said flight at which reversal of direction occurs.

10. Machine according to claim 2 wherein said oneway coupling is located at the trailing end of said slidable rack as viewed in direction of the drawing stroke. 

1. Reciprocating carriage drawing machine comprising first guideways extending in a given drawing direction, a drawing carriage reciprocably mounted in said first guideways, revolving cam means operatively connected to said drawing carriage for reciprocating the same along said first guideways, an intermediate carriage interposed between said drawing carriage and said cam means for lengthening the stroke of said drawing carriage, said intermediate carriage being also operatively connected to said cam means and being similarly reciprocable thereby in second guideways in said given drawing direction, and step-up transmission means for increasing the length of stroke of said drawing carriage comprising at least one axle carried by said intermediate carriage and extending substantially perpendicularly to said given drawing direction, a machine frame, two stationary racks mounted on opposite sides of said machine frame, said transmission means comprising two pinion means mounted side-by-side on said intermediate carriage, said two pinion means being in respective meshing engagement at one side thereof with said stationary racks and on the other side thereof with a rack slideable in third guideways parallel to said drawing direction, said slideable rack being disposed between said two pinion means and carrying rack teeth on each side thereof respectively meshing with said two pinion means.
 2. Reciprocating carriage drawing machine comprising first guideways extending in a given drawing direction, a drawing carriage reciprocatingly mounted in said first guideways, revolving cam means operatively connected to said drawing carriage for reciprocating the same along said first guideways, an intermediate carriage interposed between said drawing carriage and said cam means for lengthening the stroke of said drawing carriage, said intermediate carriage being also operatively connected to said cam means and being similarly reciprocable thereby in second guideways in said given drawing direction, and step-up transmission means for increasing the length of stroke of said drawing carriage comprising at least one axle carried by said intermediate carriage and extending substantially perpendicularly to said given drawing direction, pinion means loosely mounted on said axle and being in meshing engagement at one side thereof with a stationary rack and on the other side thereof with a rack slidable in third guideways parallel to said drawing direction, said slidable rack being coupled to said drawing carriage by a one-way coupling effective only in said given drawing direction.
 3. Reciprocating carriage drawing machine comprising first guideways extending in a given drawing direction, a drawing carriage reciprocably mounted in said first guideways, revolving cam means operatively connected to said drawing carriage for reciprocating the same along said first guideways, an intermediate carriage interposed between said drawing carriage and said caM means for lengthening the stroke of said drawing carriage, said intermediate carriage being also operatively connected to said cam means and being similarly reciprocable thereby in second guideways in said given drawing direction, and step-up transmission means for increasing the length of stroke of said drawing carriage comprising at least on axle carried by said intermediate carriage and extending substantially perpendicularly to said given drawing direction, pinion means loosely mounted on said axle and being in meshing engagement at one side thereof with a stationary rack and on the other side thereof with a rack slidable in third guideways parallel to said drawing direction, said slidable rack being coupled to said drawing carriage, said third guideways being mounted on said intermediate carriage and said first and second guideways for said drawing and said intermediate carriages respectively, are mounted in rails located above one another.
 4. Reciprocating carriage drawing machine comprising first guideways extending in a given drawing direction, a drawing carriage reciprocably mounted in said first guideways, revolving cam means operatively connected to said drawing carriage for reciprocating the same along said first guideways, an intermediate carriage interposed between said drawing carriage and said cam means for lengthening the stroke of said drawing carriage, said intermediate carriage being also operatively connected to said cam means and being similarly reciprocable thereby in second guideways in said given drawing direction, and step-up transmission means for increasing the length of stroke of said drawing carriage comprising at least one axle carried by said intermediate carriage and extending substantially perpendicularly to said given drawing direction, pinion means loosely mounted on said axle and being in meshing engagement at one side thereof with a stationary rack and on the other side thereof with a rack slidable in third guideways parallel to said drawing direction, said slidable rack being coupled to said drawing carriage, said pinion means being in the form of a double pinion, the pinions of said pinion means having different numbers of teeth, one of the pinions of said pinion means being in meshing engagement with said stationary rack and the other of the pinion of said pinion means being in meshing engagement with said slideable rack.
 5. Machine according to claim 1 wherein each of said pinion means is in the form of a double pinion, the two pinions os each of said pinion means having different numbers of teeth, one of the two pinions of each of said pinion means being in meshing engagement with said stationary rack, and the other of the two pinions of each of said pinion means being in meshing engagement with said slidable rack.
 6. Machine according to claim 5 wherein said double pinions have a transmission ratio lengthening the stroke of said drawing carriage beyond a ration of 2 : 1, said stationary racks extending inwardly for a distance affording space within said machine frame for accommodating the larger of the two pinions of each of said pinion means.
 7. Reciprocating carriage drawing machine comprising first guideways extending in a given drawing direction, a drawing carriage reciprocably mounted in said first guideways, revolving cam means operatively connected to said drawing carriage for reciprocating the same along said first guideways, an intermediate carriage interposed between said drawing carriage and said cam means for lengthening the stroke of said drawing carriage, said intermediate carriage being also operatively connected to said cam means and being similarly reciprocable thereby in second guideways in said given drawing direction, and step-up transmission means for increasing the length of stroke of said drawing carriage comprising at least one axle carried by said intermediate carriage and extending substantially perpendicularly to said given drawing direction, pinion means loosely mounted on said axle and beinG in meshing engagement at one side thereof with a stationary rack and on the other side thereof with a rack slidable in third guideways parallel to said drawing direction, said slidable rack being coupled to said drawing carriage, said pinion means being formed of two parts meeting in a median center plane thereof, and means for relatively adjusting and locking the teeth of both said parts thereof for equalizing wear of the flanks of the teeth.
 8. Reciprocating carriage drawing machine comprising first guideways extending in a given drawing direction, a drawing carriage reciprocably mounted in said first guideways, revolving cam means operatively connected to said drawing carriage for reciprocating the same along said first guideways, an intermediate carriage interposed between said drawing carriage and said cam means for lenghtening the stroke of said drawing carriage, said intermediate carriage being also operatively connected to said cam means and being similarly reciprocable thereby in second guideways in said given drawing direction, and step-up transmission means for increasing the length of stroke of said drawing carriage comprising at least one axle carried by said intermediate carriage and extending substantially perpendicularly to said given drawing direction, pinion means loosely mounted on said axle and being in meshing engagement at one side thereof with a stationary rack and on the other side thereof with a rack slidable in third guideways parallel to said drawing direction, said slidable rack being coupled to said drawing carriage, said racks being formed of two parts respectively, meeting in a median center plane thereof, and means for relatively adjusting and locking the teeth of both said parts thereof for equalizing wear of the flanks of the teeth of said racks.
 9. Reciprocating carriage drawing machine comprising first guideways extending in a given drawing direction, a drawing carriage reciprocably mounted in said first guideways, revolving cam means operatively connected to said drawing carriage for reciprocating the same along said first guideways, an intermediate carriage interposed between said drawing carriage and said cam means for lengthening the stroke of said drawing carriage, said intermediate carriage being also operatively connected to said cam means and being similarly reciprocable thereby in second guideways in said given drawing direction, and step-up transmission means for increasing the length of stroke of said drawing carriage comprising at least one axle carried by said intermediate carriage and extending substantially perpendicularly to said given drawing direction, pinion means loosely mounted on said axle and being in meshing engagement at one side thereof with a stationary rack and on the other side thereof with a rack slidable in third guideways parallel to said drawing direction, said slidable rack being coupled to said drawing carriage, said intermediate carriage having load-bearing rollers engageable with one side of a flight formed on said rotary cam, said flight being widened on a side thereof facing away from said load-bearing rollers in a region of said flight at which reversal of direction occurs.
 10. Machine according to claim 2 wherein said one-way coupling is located at the trailing end of said slidable rack as viewed in direction of the drawing stroke. 